Minerva filed a complaint in federal court in San Francisco on Tuesday saying it may seek an injunction blocking U.S. sales of Hologic’s NovaSure Advanced system which began in February. The product was launched in Europe, Canada and Australia in 2016.

Minerva’s rival device won pre-market approval from the U.S. Food and Drug Administration in July 2015, but has yet to be launched.

Hologic spokeswoman Jane Mazur said the company does not comment on pending litigation.

Hologic, based in Marlborough, Massachusetts, bills NovaSure Advanced as a next generation version of its device introduced in 2001. NovaSure generated about 8 percent of Hologic’s $2.83 billion in revenue in fiscal 2016.

Minerva, based in Redwood City, California, said its rival system has a post-treatment success rate of 91.8 percent compared with 77.7 percent for NovaSure Advanced.

Minerva has raised about $114 million from investors since its inception in 2008, and announced a $16.7 million funding round in December. Its backers include the venture capital firms New Enterprise Associates and Versant Ventures.